A known approach to cleanspace-assisted fabrication of materials such as semi-conductor substrates is to assemble a manufacturing facility as a “cleanroom.” In such cleanrooms, processing tools are arranged to provide aisle space for human operators or automation equipment. Exemplary cleanroom design is described in: “Cleanroom Design, Second Edition,” edited by W. Whyte, published by John Wiley & Sons, 1999, ISBN 0-471-94204-9, (herein after referred to as “the Whyte text”).
Cleanroom design has evolved over time to include locating processing stations within clean hoods. Vertical unidirectional air flow can be directed through a raised floor, with separate cores for the tools and aisles. It is also known to have specialized mini-environments which surround only a processing tool for added space cleanliness. Another known approach includes the “ballroom” approach, wherein tools, operators and automation all reside in the same cleanroom.
Evolutionary improvements have enabled higher yields and the production of devices with smaller geometries. However, known cleanroom design has disadvantages and limitations.
For example, as the size of tools has increased and the dimensions of cleanrooms have increased, the volume of cleanspace that is controlled has concomitantly increased. In addition, the size of currently known fabricator processing tools and their floor space mounting surfaces and utility connections result in fabs with ever increasing floor space footprints. Consequently, the cost of building the cleanspace, and the cost of maintaining the cleanliness of such cleanspace, has increased considerably.
Tool installation in a cleanroom can be difficult. The initial “fit up” of a “fab” with tools, when the floor space is relatively empty, can be relatively straight forward. However, as tools are put in place and a fab begins to process substrates, it can become increasingly difficult and disruptive of job flow, to either place new tools or remove old ones. In some embodiments, it is desirable therefore to reduce installation difficulties attendant to dense tool placement while still maintaining such density, since denser tool placement otherwise affords substantial economic advantages relating to cleanroom construction and maintenance.
The size of substrate has increased over time as have the typical sizes of fabs. The increased size allows for economies of scale in production, but also creates economic barriers to development and new entries into the industry. A similar factor is that the processing of substrates is coordinated and controlled by batching up a number of substrates into a single processing lot. A single lot can include, for example, 25 substrates. Accordingly, known carriers are sized to typically accommodate the largest size lot that is processed in a fab.
It could be desirable to have manufacturing facilities for cleanspace-assisted fabrication, that use less cleanspace area, permit dense tool placement while maintaining ease of installation, which permit the use of more simple robotics and which are capable of efficiently processing a single substrate.